Anybody figured out what is the most damaging low parry for Jinpachi is?

Also, incase anybody is still figuring out what is Jinpachi's spirit bomb notation, there isn't such a thing. The combo video is just a pre programmed tag combo that can be done by:
Kaz, ws2~5 and then you mash 1+2 all the way.

In my experience so far, u/b+1,2 hasn't actually picked up off the floor like we've seen in some of the older vids, if u/b+1 hits but doesn't B! (and it won't after low parry obviously). So if memory serves, I think the u/b+1 might spike in your juggle, making everything afterwards miss. If you could get the u/b+1 to whiff though, maybe the rest would land?

I still haven't experimented with it but I think u/b+1 should be one of our main choices in the post u+4 mixup scenario. If they stay down the u/b+1 hits grounded, but if they quickstand or roll it will B! (from my understanding). Less damage once they stay down, but covers more possibilities than another u+4 after the first one. When they start laying you can d+1+2 if you want a bit more damage, though you do lose the reset situation you get if you stomp.

I like the sound of your idea though, we should definitely try this out. So you're thinking like d/f+2, u+4, d/f+1,1, d/f+3,1 B! u/b+1 -> stuff?

Yes! Exactly like that. And df2, u4, df11 works? I only thought it works if we get a somewhat high tag launcher like EWGF~5.

d21 is definitely one of his top 10. At least 50% of the time, retaliation of jabs will whiff after a blocked d2 meaning you can df2, or even db31 to crush highs.
d21 on hit will make the next d21 uninterruptible.
d2 ch1 gives ws3 b1+2 b!. I've read somewhere ws3, df11 df31 works as well.
And for some reason, (d2)1 hits grounded/side roll+stay on the ground and will give a juggle if they wake up 3/4. I'm pretty sure it will float the opponent up if they quick stand/back roll for a u4 b1+2 b!

d1 is not -8 on hit/block. Its -9 on block and +6 on hit/ch but opponent recovers crouching. But that means we can have an uninterruptible u4. -9 on block isn't so bad either, considering the range between you and the opponent is so huge that generally jabs and even df1s will whiff.

I leave quite a gap between the second and third hit, then spam the shit out of 2, and I'm landing probably three quarters of them now. So something like 1,1<22222 Wait for the animation of the second hit to have just about finished before you start the 2's.

f/b3+4, 2 on hit gives free d21
b12 on hit and the opponent doesn't hold back, free f1+4
fb1 on hit and the opponent doesn't hold back, free f3+4,1
ws(1)1 on CH (the part when the opponent falls down from the 2nd hit), free d1 b! on bears or ub15 b! for everybody else.
d1 after u4 on kuma gives b!